I have installed very few casement windows, mostly due to regional tastes that skew heavily toward double-hungs. Of the ones I did, Anderson and Simonton both had decent products. When it comes to French doors, I would install whatever Anderson product suits your budget. If you are talking a true French, with both doors active, I am not a fan, and generally succeeded in talking the customer out of them. They tend to be finicky, and never seem to remain perfectly adjusted or well sealed, in the fairly harsh climate of the PA. mountains. where I live. Anderson, and maybe others, have a well designed adjustable hinge system that at least gives you a chance to address the frequent issues that French door can suffer from. Generally, I would avoid all vinyl doors when it comes to big openings, in particular, lower end vinyl sliders can be a real PITA over time.
Since vinyl windows now dominate the market, and they are all very similar in construction, and fairly low cost to produce, it is possible to find good ones, relatively cheaply, if you research and shop aggressively. OTOH, when it comes to things like French doors and sliding patio doors, I don't think the same is true. More expensive, name brand doors, in the middle of a company's product line, seem to be worth the extra cost, over time.
